Methods and apparatus for loading and unloading substrate carriers on moving conveyors using feedback

ABSTRACT

The present invention provides systems and methods for loading and unloading substrate carriers onto and off of a transport system. The invention includes a substrate carrier handler adapted to transfer a substrate carrier between a docking station and a transport system, the substrate carrier handler including an end effector adapted to support the substrate carrier; a controller coupled to the substrate carrier handler and operative to control the substrate carrier handler such that the end effector of the substrate carrier handler is operative to selectively engage and disengage the substrate carrier to and from the transport system while the substrate carrier is in motion; and a sensor coupled to the controller and operative to provide a signal to the controller indicative of information about the substrate carrier. The controller is operative to adjust operation of the substrate carrier handler based on the signal from the sensor if the adjustment may be performed within a load or unload stroke of the substrate carrier handler. Numerous other aspects are provided.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 60/828,070, filed Oct. 4, 2006 and titled “Methods And Apparatus ForLoading And Unloading Substrate Carriers On Moving Conveyors UsingFeedback,” which is hereby incorporated by reference herein in itsentirety.

This application is also a continuation-in-part of U.S. patentapplication Ser. No. 10/987,452 filed Nov. 12, 2004 now U.S. Pat. No.7,684,895 and titled “Wafer Loading Station that Automatically Retractsfrom a Moving Conveyor in Response to an Unscheduled Event”, whichclaims priority to U.S. Provisional Patent Application Ser. No.60/520,140, filed Nov. 13, 2003, and is also a continuation-in-part ofU.S. patent application Ser. No. 10/650,480, filed Aug. 28, 2003 nowU.S. Pat. No. 7,243,003 and titled “Substrate Carrier Handler ThatUnloads Substrate Carriers Directly From a Moving Conveyor”, whichclaims priority from U.S. Provisional Application Ser. Nos. 60/407,463,filed Aug. 31, 2002 and 60/443,004, filed Jan. 27, 2003. Each of theabove patent applications is hereby incorporated by reference herein inits entirety.

The present application is also related to the followingcommonly-assigned, co-pending U.S. Patent Applications, each of which ishereby incorporated herein by reference in its entirety for allpurposes:

U.S. patent application Ser. No. 10/650,310, filed Aug. 28, 2003 andtitled “System For Transporting Substrate Carriers”;

U.S. patent application Ser. No. 10/650,312, filed Aug. 28, 2003 andtitled “Method and Apparatus for Using Substrate Carrier Movement toActuate Substrate Carrier Door Opening/Closing”;

U.S. patent application Ser. No. 10/650,481, filed Aug. 28, 2003 andtitled “Method and Apparatus for Unloading Substrate Carriers fromSubstrate Carrier Transport Systems”;

U.S. patent application Ser. No. 10/650,479, filed Aug. 28, 2003 andtitled “Method and Apparatus for Supplying Substrates to a ProcessingTool”;

U.S. Provisional Patent Application No. 60/407,452, filed Aug. 31, 2002and titled “End Effector Having Mechanism For Reorienting A WaferCarrier Between Vertical And Horizontal Orientations”;

U.S. Provisional Patent Application No. 60/407,337, filed Aug. 31, 2002,and titled “Wafer Loading Station with Docking Grippers at DockingStations”;

U.S. patent application Ser. No. 10/650,311, filed Aug. 28, 2003 andtitled “Substrate Carrier having Door Latching and Substrate ClampingMechanism”;

U.S. patent application Ser. No. 10/764,982, filed Jan. 26, 2004 andtitled “Methods and Apparatus for Transporting Substrate Carriers”;

U.S. patent application Ser. No. 10/764,820, filed Jan. 26, 2004, andtitled “Overhead Transfer Flange and Support for Suspending SubstrateCarrier”;

U.S. Provisional Patent Application No. 60/443,115, filed Jan. 27, 2003,and titled “Apparatus and Method for Storing and Loading WaferCarriers”;

U.S. Provisional Patent Application No. 60/520,180, filed Nov. 13, 2003,and titled “Calibration of High Speed Loader to Substrate TransportSystem”; and

U.S. Provisional Patent Application No. 60/520,035, filed Nov. 13, 2003,and titled “Apparatus and Method for Transporting Substrate CarriersBetween Conveyors”.

FIELD OF THE INVENTION

The present invention relates generally to semiconductor devicefabrication systems, and is more particularly concerned withtransportation of wafer carriers within a fabrication facility.

BACKGROUND OF THE INVENTION

Manufacturing of semiconductor devices typically involves performing asequence of procedures with respect to a substrate such as a siliconsubstrate, a glass plate, etc. (Such substrates may also be referred toas wafers, whether patterned or unpatterned.) These steps may includepolishing, deposition, etching, photolithography, heat treatment, and soforth. Usually a number of different processing steps may be performedin a single processing system or “tool” which includes a plurality ofprocessing chambers. However, it is generally the case that otherprocesses are required to be performed at other processing locationswithin a fabrication facility, and it is accordingly necessary thatsubstrates be transported within the fabrication facility from oneprocessing location to another. Depending upon the type of semiconductordevice to be manufactured, there may be a relatively large number ofprocessing steps required to be performed at many different processinglocations within the fabrication facility.

It is conventional to transport substrates from one processing locationto another within substrate carriers such as sealed pods, cassettes,containers and so forth. It is also conventional to employ automatedsubstrate carrier transport devices, such as automatic guided vehicles,overhead transport systems, substrate carrier handling robots, etc., tomove substrate carriers from location to location within the fabricationfacility or to transfer substrate carriers from or to a substratecarrier transport device.

For an individual substrate, the total fabrication process, fromformation or receipt of the virgin substrate to cutting of semiconductordevices from the finished substrate, may require an elapsed time that ismeasured in weeks or months. In a typical fabrication facility, a largenumber of substrates may accordingly be present at any given time as“work in progress” (WIP). The substrates present in the fabricationfacility as WIP may represent a very large investment of workingcapital, which tends to increase the per substrate manufacturing cost.It would therefore be desirable to reduce the amount of WIP for a givensubstrate throughput for the fabrication facility. To do so, the totalelapsed time for processing each substrate should be reduced.

SUMMARY OF THE INVENTION

In some aspects, the present invention provides a system for loading andunloading substrate carriers onto and off of a transport system. Thesystem includes a substrate carrier handler adapted to transfer asubstrate carrier between a docking station and a transport system, thesubstrate carrier handler including an end effector adapted to supportthe substrate carrier; a controller coupled to the substrate carrierhandler and operative to control the substrate carrier handler such thatthe end effector of the substrate carrier handler is operative toselectively engage and disengage the substrate carrier to and from thetransport system while the substrate carrier is in motion; and a sensorcoupled to the controller and operative to provide a signal to thecontroller indicative of information about the substrate carrier. Thecontroller is operative to adjust operation of the substrate carrierhandler based on the signal from the sensor if the adjustment may beperformed within a load or unload stroke of the substrate carrierhandler.

In yet other aspects, the present invention provides a method of loadingand unloading substrate carriers onto and off of a transport system. Themethod includes sensing information about an approaching substratecarrier being transported on a transport system; determining a substratecarrier type for the approaching substrate carrier; selecting an unloadmotion profile from among at least two stored motion profiles based onthe information and based on the substrate carrier type; and unloadingthe substrate carrier from the transport system using the selectedunload motion profile. In some embodiments, the method further includesadjusting the unload motion profile based on additional informationsensed during an unload stroke of a substrate carrier handler.

In still some other aspects, the present invention provides a method ofloading and unloading substrate carriers onto and off of a transportsystem. The method includes determining an available substrate carriersupport on a transport system; sensing first information about thesubstrate carrier support; sensing second information about a substratecarrier to be loaded onto the substrate carrier support; determining asubstrate carrier type for the substrate carrier; selecting an loadmotion profile from among at least two stored motion profiles based onthe first and second information and based on the substrate carriertype; and loading the substrate carrier from the transport system usingthe selected load motion profile.

Other features and aspects of the present invention will become morefully apparent from the following detailed description, the appendedclaims and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of a conventional arrangement of a processingtool and an associated wafer carrier loading and storage apparatus;

FIG. 2A is a front elevational view of a substrate loading stationprovided in accordance with the present invention;

FIG. 2B is a side elevational view of a portion of the substrate loadingstation of FIG. 2A useful in describing an exemplary embodiment of afirst sensor of the substrate loading station;

FIG. 2C is a perspective view of a portion of the end effector of FIG.2A illustrating an exemplary second sensor of the substrate loadingstation of FIG. 2A;

FIG. 2D is an enlarged perspective view of a portion of FIG. 2C;

FIG. 2E is a perspective view of a portion of the end effector of FIG.2A illustrating the second sensor positioned to detect a portion of acarrier engagement member;

FIG. 3 is a flow chart that illustrates an exemplary process performedin accordance with the invention to unload a wafer carrier from a movingconveyor;

FIGS. 4A-4E are schematic side views showing various stages of theprocess of FIG. 3;

FIG. 5 is a flow chart that illustrates an exemplary process performedin accordance with the invention to load a wafer carrier onto a movingconveyor;

FIGS. 6A-6E are schematic side views showing various stages of theprocess of FIG. 5;

FIGS. 7A and 7B are simplified front elevational views of the inventivewafer loading station, similar to FIG. 2;

FIGS. 7C-7D are simplified schematic side views illustrating a movingconveyor similar to FIGS. 4A-4E and 6A-6E;

FIGS. 8A-8D are exemplary motion profiles for the end effector of thepresent invention;

FIGS. 9A-9B are side elevational views of a wafer carrier loadingstation in accordance with the present invention adjacent a rotatableconveyor of a wafer carrier transport system, wherein the wafer loadingstation inventively comprises a biasing device;

FIG. 10 is a rear elevational view illustrating the wafer carrierhandler of the wafer carrier loading station of FIGS. 9A-9B, the wafercarrier handler comprising a biasing device coupled to each verticalguide of the wafer carrier handler;

FIG. 11 is a rear elevational view illustrating the wafer carrierhandler of the wafer carrier loading station of FIGS. 9A-9B operativelycoupled to a controller, the controller being further coupled to anuninterruptible power supply; and

FIG. 12 is a simplified front, elevational view of an alternativeretraction mechanism for moving an end effector of a wafer loadingstation away from a conveyor.

DETAILED DESCRIPTION

A wafer carrier handler at a wafer loading station includes a horizontalguide that is moveable vertically along parallel vertical guides, and anend effector that is moveable horizontally along the horizontal guide.To unload a wafer carrier from a moving conveyor that transfers wafercarriers (a “wafer carrier conveyor”) and that passes by the waferloading station, the end effector is moved along the horizontal guide ata velocity that substantially matches the velocity of the wafer carrier(e.g., by substantially matching wafer carrier speed in a horizontaldirection). In addition, the end effector may be maintained in aposition adjacent the wafer carrier. The end effector thus maysubstantially match a position of the wafer carrier while substantiallymatching a velocity of the wafer carrier. Likewise, conveyor positionand/or velocity may be substantially matched.

While the end effector substantially matches the wafer carrier'svelocity (and/or position), the end effector is raised, by moving thehorizontal guide upwardly along the vertical guides, so that the endeffector contacts the wafer carrier and disengages the wafer carrierfrom the wafer carrier conveyor. A wafer carrier similarly may be loadedonto the moving wafer carrier conveyor by substantially matching endeffector and conveyor velocities (and/or positions) during loading. Inaccordance with the present invention, apparatuses and methods areprovided to remove the end effector from the conveyor's path upon theoccurrence of a unscheduled event, such as a power failure or anemergency shut down. These apparatuses and methods are described indetail with reference to FIGS. 9-11.

Previously incorporated U.S. patent application Ser. No. 10/650,310,filed Aug. 28, 2003 and titled “System For Transporting SubstrateCarriers”, discloses a substrate carrier transport system that includesa conveyor for substrate carriers that is intended to be constantly inmotion during operation of the fabrication facility which it serves. Theconstantly moving conveyor is intended to facilitate transportation ofsubstrates within the fabrication facility so as to reduce the total“dwell” time of each substrate in the fabrication facility; therebyreducing WIP, and cutting capital and manufacturing costs. To operate afabrication facility in this manner, methods and apparatus should beprovided for unloading substrate carriers from the conveyor, and forloading substrate carriers onto the conveyor, while the conveyor is inmotion.

In accordance with at least one aspect of the invention, a substratecarrier handler at a substrate loading station includes a horizontalguide that is moveable vertically along parallel vertical guides, and anend effector that is moveable horizontally along the horizontal guide.To unload a substrate carrier from a moving conveyor that transferssubstrate carriers (a “substrate carrier conveyor”) and that passes bythe substrate loading station, the end effector is moved along thehorizontal guide at a velocity that substantially matches the velocityof the substrate carrier as it is being transported by the substratecarrier conveyor (e.g., by substantially matching substrate carrierspeed in a horizontal direction). In addition, the end effector may bemaintained in a position adjacent the substrate carrier as the substratecarrier is being transported. The end effector thus may substantiallymatch a position of the substrate carrier while substantially matching avelocity of the substrate carrier. Likewise, conveyor position and/orvelocity may be substantially matched.

While the end effector substantially matches the substrate carrier'svelocity (and/or position), the end effector is raised, by moving thehorizontal guide upwardly along the vertical guides, so that the endeffector contacts the substrate carrier and disengages the substratecarrier from the substrate carrier conveyor. A substrate carriersimilarly may be loaded onto the moving substrate carrier conveyor bysubstantially matching end effector and conveyor velocities (and/orpositions) during loading. In at least one embodiment of the invention,such substrate carrier handoffs between the end effector and substratecarrier conveyor are performed at a substantially zero velocity and/oracceleration between the end effector and the substrate carrier.Numerous other aspects of the invention are provided, as describedfurther below.

FIG. 1 is a top plan view showing a conventional loading and storingapparatus 111 in position for storing substrate carriers adjacent aconventional processing tool 113. A factory interface (FI) 115 is shownpositioned between the loading and storage apparatus 111 and theprocessing tool 113. The loading and storage apparatus 111 is positionedadjacent a first side of a clean room wall 117 and the factory interface115 is positioned adjacent a second side of the clean room wall 117. Thefactory interface 115 includes an FI robot 119 that may movehorizontally along a track (not shown) that is parallel to the cleanroom wall 117 and may extract a substrate (not shown) from one or moresubstrate carriers 120 present at the loading and storage apparatus 111.The FI robot 119 may transport the substrate to a load lock chamber 121of the processing tool 113.

The load lock chambers 121 shown in FIG. 1 are coupled to a transferchamber 123 of the processing tool 113. Also coupled to the transferchamber 123 are processing chambers 125 and auxiliary processingchambers 127. Each of the processing chambers 125 and auxiliaryprocessing chambers 127 may be arranged to perform a conventionalsemiconductor device fabrication process such as oxidation, thin filmdeposition, etching, heat treatment, degassing, cool down, etc. Asubstrate handling robot 129 is disposed within the transfer chamber 123to transfer substrates, such as substrate 131, among the processingchambers 125, 127 and the load lock chambers 121.

The loading and storage apparatus 111 includes one or more substratecarrier storage shelves 133 for storing substrate carriers before orafter the substrates contained in the substrate carriers are processedby the processing tool 113. The loading and storage apparatus 111 alsoincludes one or more docking stations (which are not shown but may be,for example, below the storage shelves 133). A substrate carrier may bedocked at a docking station for extraction of substrates therefrom bythe FI robot 119. Also included in the loading and storage apparatus 111is a factory load location 135, at which a substrate carrier transportdevice, such as an automatic guided vehicle (AGV), may deposit or pickup a substrate carrier.

The loading and storage apparatus 111 further includes a substratecarrier handler 137 which is adapted to move substrate carriers amongthe factory load location 135, the storage shelves 133 and the dockingstations.

In line with the above-noted goal of facilitating transport ofsubstrates within a fabrication facility, it may be desirable totransport substrate carriers to and from a substrate loading stationsuch as the loading and storage apparatus 111 by means of a substratecarrier conveyor that is constantly in motion (e.g., to reduce dwelltime and thus work in progress and manufacturing costs). Consequently,in accordance with the present invention, an inventive substrate loadingstation is provided that can unload substrate carriers from a substratecarrier conveyor, and that can load substrate carriers onto thesubstrate carrier conveyor, while the substrate carrier conveyor ismoving.

An embodiment of the invention will now be described with reference toFIGS. 2A-6E. FIG. 2A is a front elevational view of a substrate loadingstation 201 provided in accordance with the invention. Although notshown in FIG. 2A, it should be understood that the inventive substrateloading station 201 may be associated with a processing tool and/orfactory interface of the kind described in connection with FIG. 1.

The substrate loading station 201 may include one or more load ports orsimilar locations where substrates or substrate carriers are placed fortransfer to and/or from a processing tool (e.g., one or more dockingstations 203, although transfer locations that do not employdocking/undocking movement may be employed). In the particularembodiment shown in FIG. 2A, the substrate loading station 201 includesa total of eight docking stations 203, arranged in two columns 205 offour docking stations each. Other numbers of columns and/or dockingstations may be employed. Each docking station 203 is adapted to supportand/or dock a substrate carrier 207 at the docking station 203 and toallow a substrate (not shown) to be extracted from the substrate carrier207 at the docking station 203 and transferred to a processing tool suchas the processing tool 113 of FIG. 1 (e.g., by a factory interfacerobot, such as the factory interface robot 119 of FIG. 1). In oneembodiment of the invention, the substrate carriers 207 are singlesubstrate carriers. “Single substrate carrier” will be understood tomean a substrate carrier shaped and sized to contain only one substrateat a time. Substrate carriers that hold more than one substrate also maybe employed (e.g., 25 or any other number). (Alternatively, one or moredocking stations 203 may be adapted to directly support a substratewithout a substrate carrier). Each docking station 203 may beconfigured, for example, as described in previously incorporated U.S.Patent Application Ser. No. 60/407,337, filed Aug. 31, 2002 and titled“Wafer Loading Station with Docking Grippers at Docking Stations”. Otherdocking station configurations may be employed.

Each docking station 203 may include a port 209 through which asubstrate may be transferred to the factory interface (e.g., factoryinterface 115 in FIG. 1). Adjacent each port 209 is a docking gripper211 which is adapted to suspend a substrate carrier 207 and to move thesuspended substrate carrier between a docked and undocked position. Amoveable stage or other support (not shown) alternatively may beemployed to support (e.g., from below or otherwise) and/or dock/undockeach substrate carrier 207 at each docking station 203. Each port 209may also include a substrate carrier opener 213 which, in one aspect, isadapted to employ docking movement of a substrate carrier 207 to openthe substrate carrier 207 as it moves from an undocked position to adocked position as described in previously incorporated U.S. patentapplication Ser. No. 10/650,312, filed Aug. 28, 2003 and titled “Methodand Apparatus for Using Substrate Carrier Movement to Actuate SubstrateCarrier Door Opening/Closing”. Each substrate carrier 207 may have, forexample, the carrier door latching and/or substrate clamping featuresdisclosed in previously incorporated U.S. patent application Ser. No.10/650,311, filed Aug. 28, 2003 and titled “Substrate Carrier havingDoor Latching and Substrate Clamping Mechanism”. Other substrate carrieropener, door latching, and/or substrate clamping configurations may beemployed.

The substrate loading station 201 also includes a substrate carrierhandler 215 which operates in accordance with an aspect of theinvention. In one or more embodiments of the invention, the substratecarrier handler 215 includes a pair of vertical guides 217, 219 and ahorizontal guide 221 which is mounted for vertical movement on thevertical guides 217, 219. A belt drive or a lead screw and an associatedmotor or motors (which are not shown) or other suitable mechanism isprovided to drive the horizontal guide 221 for vertical movement alongthe vertical guides 217, 219. A support 223 is mounted on the horizontalguide 221 for horizontal movement along the horizontal guide 221. A beltdrive or lead screw, and associated motor or motors (which are notshown) or other suitable mechanism is provided to move the support 223horizontally along the horizontal guide 221.

In at least one embodiment of the invention, the vertical guides 217,219 may each comprise an integrated guide/driving mechanism such as PartNo. 1140-260-10, 1768 mm available from Bosch, Inc. Likewise, thehorizontal guide 221 may comprise an integrated guide/driving mechanismsuch as Part No. 1140-260-10, 1468 mm also available from Bosch, Inc.Other guide/driving mechanism systems may be employed.

An end effector 225 is mounted on the support 223. The end effector 225may be, for example, in the form of a horizontally-oriented platform 227adapted to support a substrate carrier (e.g., one of the substratecarriers 207). In at least one embodiment, the platform 227 may havekinematic pins or other kinematic positioning features 229. (Althoughonly two kinematic features 229 are shown in FIG. 2A, other numbers ofkinematic pins or features such as three or more may be provided on theplatform 227.) The kinematic features 229 may cooperate with concave orotherwise shaped features (not shown in FIG. 2A) on the bottom of thesubstrate carrier 207 to guide the substrate carrier 207 into correct(positive) positioning on the platform 227. In at least one embodimentof the invention, the end effector 225 may comprise, for example, an endeffector capable of changing the orientation of a substrate carrier fromvertical to horizontal and vice versa as described in previouslyincorporated U.S. Patent Application Ser. No. 60/407,452, filed Aug. 31,2002 and titled “End Effector Having Mechanism For Reorienting A WaferCarrier Between Vertical And Horizontal Orientations”. Any othersuitable end effector also may be employed.

A continuously or otherwise moving conveyor, schematically representedby an arrow 231, is positioned above the substrate loading station 201and the substrate carrier handler 215. The conveyor 231 is adapted totransport substrate carriers such as the substrate carriers 207 to andfrom the substrate loading station 201. In one embodiment of theinvention, the continuously moving conveyor 231 may be implemented as aribbon of stainless steel or similar material as described in previouslyincorporated U.S. patent application Ser. No. 10/764,982, filed Jan. 26,2004 and titled “Methods and Apparatus for Transporting SubstrateCarriers”. The present invention similarly may be employed with anyother type of continuously or otherwise moving conveyor.

The substrate loading station 201 may include one or more sensors 233,235 for detecting movement and/or positions of (1) the conveyor; (2)components of the conveyor 231 (e.g., components used to supportsubstrate carriers being transported by the conveyor 231 as describedfurther below with reference to FIGS. 4A-4E, 6A-6E and 7C-7D); and/or(3) substrate carriers being transported by the conveyor 231. Forexample, the sensor 233 may be mounted on the substrate loading station201, and the sensor 235 may be mounted on the end effector 225. Othersensor locations may be employed, as may any suitable sensors (e.g.,through beam sensors, reflection-based sensors, etc.).

FIG. 2B is a side elevational view of a portion of the substrate loadingstation 201 useful in describing an exemplary embodiment of the sensor233. With reference to FIG. 2B, the sensor 233 comprises a first sensorpair 233 a, 233 a′ for detecting a speed and/or position of the conveyor231; and/or position of the substrate carrier (and/or the speed withwhich a substrate carrier 207 is being transported by the conveyor 231as described further below). The sensor 233 also may include a secondsensor pair 233 b, 233 b′ for detecting whether a substrate carrier 207is being transported by the conveyor 231. For example, the first sensorpair 233 a, 233 a′ may be mounted at an elevation of the conveyor 231and the second sensor pair 233 b, 233 b′ may be mounted at an elevationat which substrate carriers are transported by the conveyor 231 as shownin FIG. 2B (e.g., via a mounting bracket B coupled to a frame F of thesubstrate loading station 201, or via another suitable mountingmechanism). Each sensor pair may comprise, for example, a Model No.M126E2LDQ light source and a Model No. Q23SN6RMHSQDP receiver availablefrom Banner, Inc. Other sensor arrangements/types may be employed.Exemplary embodiments for the sensor 235 are described further belowwith reference to FIGS. 2C-E and FIG. 3.

A controller 237 (FIG. 2A) may be coupled to the sensors 233, 235 and tothe substrate carrier handler 215 to receive input from the sensors 233,235 and to control operation of the substrate carrier handler 215 asdescribed further below. More or fewer than the two sensors 233, 235 maybe provided, and the sensors 233, 235 may be mounted at locations otherthan those shown in FIGS. 2A and 2B. The controller 237 may be the samecontroller used to control operation of a processing tool that thesubstrate loading station 201 serves, or a separate controller.

In at least one embodiment of the invention, speed of the conveyor(and/or a substrate carrier being transported by the conveyor) may bedirectly measured (rather than employing the sensor 233 to indirectlymeasure conveyor speed). For example, as shown in FIG. 2A, one or moreencoders 240 a, 240 b (described below) may be coupled to the conveyor231 and directly measure the speed of the conveyor 231 (and anysubstrate carriers being transported thereby) and provide speedinformation to the controller 237. More or fewer than two encoders maybe employed. Each encoder may comprise, for example, a U.S. Digitalencoder (e.g., an HDS6 quadrature encoder) or any other suitableencoder. A linear encoder, resolver or other positioning device also maybe employed to measure conveyor speed and/or position.

FIG. 3 is a flow chart that illustrates an exemplary process that may beperformed by the substrate loading station 201 in accordance with theinvention to unload a substrate carrier 207 from the conveyor 231. FIGS.4A-4E are schematic side views, illustrating stages of the process ofFIG. 3.

When an operation for unloading a substrate carrier 207 from theconveyor 231 is to be performed, the horizontal guide 221 of thesubstrate carrier handler 215 is positioned near the upper ends 217 a,219 a of the vertical guides 217, 219, and the support 223 is positionednear the upstream side 221 a (in the view of FIG. 2A, the left sidealthough right to left travel may be employed if the conveyor 231travels right to left) of the horizontal guide 221.

The process of FIG. 3 starts at step 301 and proceeds to step 303. Atstep 303 the controller 237 receives a signal (e.g., from the sensor 233or 235) to indicate the presence of a substrate carrier 207 that isbeing transported by the conveyor 231 and that is to be unloaded fromthe conveyor 231 by the substrate loading station 201 (a “targetsubstrate carrier 207”). For example, with reference to FIG. 2B, thesensor pair 233 b, 233 b′ may detect the target substrate carrier 207 asa light beam L associated with the sensor pair 233 b, 233 b′ is blockedby the target substrate carrier 207. Upon receipt of the sensor signal,the controller 237 controls the substrate carrier handler 215 such thatthe support 223 (with the end effector 225 attached thereto) isaccelerated in the same direction of travel as the conveyor 231 (e.g.,to the right in FIG. 2A) to substantially match the position and speedof the target substrate carrier 207 (step 305, FIG. 3). FIG. 4Aillustrates this stage of the process of FIG. 3.

In at least one embodiment of the invention, prior to accelerating theend effector 225 so that it substantially matches the position and speedof the target substrate carrier 207 (step 305), the controller 237employs the sensor 233 (or one or more of the encoders 240 a, 240 b) todetermine a speed of the conveyor 231. Position of the conveyor 231 alsomay be determined. As stated, the sensor 233 may comprise a first sensorpair 233 a, 233 a′ (FIG. 2B) for detecting a speed of the conveyor 231(and/or the speed with which a substrate carrier 207 is beingtransported by the conveyor 231), and a second sensor pair 233 b, 233 b′for detecting whether a substrate carrier 207 is being transported bythe conveyor 231. Such a speed and/or position determination may beperformed prior to or during the unloading of each target substratecarrier 207, periodically, continuously or at some other interval.

Based on the speed of the conveyor 231, the controller 237 may determinea motion profile for the end effector 225 and direct motion of the endeffector 225 in accordance with the motion profile to substantiallymatch the speed and position of the end effector 225 and targetsubstrate carrier 207. The motion profile may be “predetermined”, suchthat the controller 237 only allows the end effector 225 to beginperforming an unload operation (e.g., begin accelerating) if the speedof the conveyor 231 is within a predetermined speed range (e.g., a rangethat ensures that the end effector 225 will be properly aligned with thetarget substrate carrier 207 if the end effector 225 is accelerated,moved and/or positioned in accordance with the predetermined motionprofile); otherwise, the process of FIG. 3 ends. Such a predeterminedmotion profile may be employed even if the speed of the conveyor 231 isnot measured (e.g., assuming the speed of the conveyor 231 is maintainedwithin a predetermined speed range that ensures that the end effector225 will be properly aligned with the target substrate carrier 207 ifthe end effector 225 is accelerated in accordance with the predeterminedmotion profile).

The controller 237 may employ the speed of the conveyor 231 to determinea motion profile for the end effector 225, for example, using a look uptable of predetermined motion profiles, using an algorithm to calculatethe motion profile, etc. It will be understood that substrate carrierspeed, rather than conveyor speed may be measured and employed todetermine a motion profile or whether to employ a predetermined motionprofile for the end effector 225. Each motion profile may include all ofthe accelerations, decelerations, raisings and lowerings (describedbelow) employed by the end effector 225 during an unload operation.

As stated, in at least one embodiment of the invention, the conveyor 231may comprise a ribbon-shaped band (e.g., of stainless steel or anothersuitable material) as described in previously incorporated U.S. patentapplication Ser. No. 10/764,982, filed Jan. 26, 2004 and titled “Methodsand Apparatus for Transporting Substrate Carriers”. In such anembodiment, the conveyor 231 may be provided with slots or otheropenings (e.g., slot 231 a in FIG. 2B) spaced along the conveyor 231 atpredetermined spacings, through which a light beam of sensor pair 233 a,233 a′ (FIG. 2B) may pass as the slots of the conveyor 231 travel by thesensor pair 233 a, 233 a′. By measuring the time between two successivetransmissions of the light beam of sensor pair 233 a, 233 a′ through theconveyor 231 (via two successive slots in the conveyor) and withknowledge of the distance between the two successive slots, the speed ofthe conveyor 231 may be determined. The position of the slots 231 aabove each substrate carrier 207 (FIG. 2C) also provide the controller237 with conveyor 231 and/or substrate carrier 207 position information.

In one more embodiment of the invention, the encoders 240 a, 240 b (FIG.2A) may be employed to directly read conveyor speed. For example, eachencoder 240 a, 240 b may provide conveyor speed information to thecontroller 237 and the controller 237 may compare the informationreceived from the encoders 240 a, 240 b as part of an error checking orconfidence routine. Such speed monitoring may be performed periodically,continuously or at any other interval. By measuring conveyor speeddirectly (e.g., via one or more encoders or other positioning devices),and by determining band position via the sensor 233 (e.g., and slots 231a) handoffs of substrate carriers between the end effector 225 and theconveyor 231, while the conveyor 231 is in motion, may be preciselyperformed as described further below.

In FIG. 4A the target substrate carrier 207 is shown being transportedby the conveyor 231 by means of a carrier engagement member 401 whichengages a top flange 402 of the substrate carrier 207. Otherconfigurations for supporting the substrate carrier 207 may be employed(e.g., one or more mechanisms for supporting the substrate carrier 207by its sides, bottom or the like). One such configuration for thecarrier engagement member 401 is described in previously incorporatedU.S. patent application Ser. No. 10/764,820, filed Jan. 26, 2004, andtitled “Overhead Transfer Flange and Support for Suspending SubstrateCarrier”.

An arrow 403 indicates the direction of motion of the conveyor 231. Theend effector 225 of the substrate carrier handler 215 is illustrated inFIG. 4A in a position below the target substrate carrier 207 and beingmoved (as indicated by an arrow 405) in the same direction as theconveyor 231 at a speed that substantially matches the speed of thetarget substrate carrier 207. The end effector 225 thereby substantiallymatches a velocity (e.g., speed and direction) of the target substratecarrier 207. In addition, the end effector 225 substantially matches aposition of the target substrate carrier 207. More generally, the endeffector 225 substantially matches a motion (velocity and/or position)of the target substrate carrier 207. As used herein, “substantiallymatches” means sufficiently matches so that a substrate carrier may beunloaded from and/or loaded onto a moving conveyor and/or carrierengagement member without damaging a substrate contained within thesubstrate carrier and/or generating potentially damaging particles.

In the embodiment shown in FIG. 4A, the target substrate carrier 207moves with the conveyor 231. Accordingly, the end effector 225 alsosubstantially matches the speed, velocity, motion and/or position of theconveyor 231. There may be embodiments in which the conveyor 231 movesat a different rate, or not at all, relative to the target substratecarrier 207. For example, the carrier engagement member 401 itself maymove the target substrate carrier 207 along the conveyor 231. In thislater embodiment, the end effector 225 may not substantially match thespeed, velocity and/or position of the conveyor 231.

In one or more embodiments of the invention, the end effector 225 maynot be positioned at the same location as the trigger (or launch) sensor(e.g., sensor pair 233 b, 233 b′ of FIG. 2B) that detects the presenceof the target substrate carrier 207 on the conveyor 231. In suchinstances, it may be necessary to delay acceleration of the end effector225 in step 305 to compensate for the differing positions of the endeffector 225 and the trigger sensor. This “launch offset” may depend on,for example, the distance between the end effector 225 and the triggersensor, the speed of the conveyor 231, etc. A launch offset may beseparate from or built into a motion profile for the end effector 225.

Referring again to FIG. 3, at step 307, the position of the targetsubstrate carrier 207 relative to the end effector 225 is detected(e.g., via a signal or signals from the sensor 235 (FIG. 2A)). Forexample, if the sensor 235 comprises a light source/detector pair, suchas a Model No. QS30 sensor system available from Banner, Inc. or thelike, the sensor 235 may emit a beam of light toward the targetsubstrate carrier 207 that is only detected by the sensor 235 if the endeffector 225 is properly positioned relative to the target substratecarrier 207 (e.g., by providing the substrate carrier 207 with anappropriate reflective surface and/or surface topography such as anangled notch that reflects light toward the sensor 235 only when the endeffector 225 is properly positioned relative to the substrate carrier207). FIG. 2C is a perspective view of a portion of the end effector 225illustrating an exemplary sensor 235 positioned to detect a light beam241 (FIG. 2D) reflected from a notch 243 formed in a portion of a targetsubstrate carrier 207 when the end effector 225 is properly positionedrelative to the target substrate carrier 207. FIG. 2D is an enlargedperspective view of a portion of FIG. 2C. As shown in FIGS. 2C-2D, thesensor 235 may be coupled to the end effector 225 via a suitable bracketor other support structure 247. Other configurations may be employed.

In at least one embodiment of the invention, if the end effector 225 isnot properly positioned relative to the target substrate carrier 207,then the process of FIG. 3 ends. Alternatively, in another embodiment ofthe invention, any necessary adjustments in the position of the endeffector 225 relative to the target substrate carrier 207 may be made(step 309). For example, the controller 237 may accelerate and/ordecelerate the end effector 225 until a proper alignment signal isreceived from the sensor 235 so as to ensure that kinematic pins 229(FIG. 4A) are properly positioned below alignment features (e.g.,concave or otherwise-shaped features 407) of the target substratecarrier 207. It will be appreciated that the steps 307 and 309 areperformed while the target substrate carrier 207 and the end effector225 are in motion, and are performed so that the end effector 225 ispositioned below the target substrate carrier 207 while substantiallymatching speed therewith. Accordingly, the end effector 225 is moved soas to remain adjacent and below the target substrate carrier 207 whilethe target substrate carrier 207 is in motion.

It will be understood that the relative position of the target substratecarrier 207 and the end effector 225 may be detected and adjustednumerous times (or continuously), and that a feedback control loop(e.g., signals from sensors 233, 235 and/or encoders 240 a, 240 b fed tocontroller 237 which is coupled to and adapted to control the speed andposition of end effector 225 of the substrate carrier handler 215 asdepicted in FIG. 2A) may be employed to ensure that the speed and/orposition of the end effector 225 remain substantially matched with thatof the target substrate carrier 207. In yet another embodiment of theinvention, steps 307 and 309 may be eliminated (e.g., if a predeterminedmotion profile is employed that is correlated to the speed of theconveyor 231 and launch time/position of the end effector 225). In suchan embodiment, the sensor 235 may be eliminated.

In place of or in addition to the sensor 235, the encoder 240 a and/or240 b may be employed to monitor conveyor speed during an unload/loadoperation. In response to gross deviations in conveyor speed during anunload/load operation, the controller 237 may abort the unload/loadoperation (e.g., by employing another motion profile that ensures thatthe end effector 225 does not interfere with the conveyor 231 orsubstrate carriers being transported thereby). Gross deviations mayinclude variations wherein the speed difference between the targetsubstrate carrier 207/carrier engagement member 401 and the end effector225 is too large to adjust for within the “stroke” (e.g., the horizontalrange of motion of the end effector 225) of the substrate carrierhandler 215. In other words, for example, if the target substratecarrier 207 is traveling so fast that the end effector 225 is unable tomatch the target substrate carrier's speed as the target substratecarrier 207 passes the substrate carrier handler 215, the controller 237may abort an unload operation by not elevating the end effector 225.

Alternatively, for non-gross conveyor speed variations, the controller237 may adjust end effector position (e.g., via accelerations ordecelerations) to ensure proper unload (or load) operations. A closedloop feedback system including the end effector 225, the sensor 233, theencoders 240 a and/or 240 b and/or the controller 237 thereby may ensureproper unload (or load) operations despite conveyor speed variations.

In some embodiments, a combination of a closed loop feedback system andan open loop feedback system may be employed. In an embodiment employingan open loop feedback system, the controller 237 of the substratecarrier handler 215 may receive a signal from one or more sensors 233,235 and/or encoders 240 a, 240 b and may trigger a predetermined motionprofile of the end effector 225 based on the signal(s). In someembodiments, the predetermined motion profile may be selected from adatabase of motion profiles stored in the controller 237. The selectedprofile may be chosen to best match the size and/or type of the carrier207 and/or the speed of the conveyor 231 measured at a point on theconveyor 231 disposed just before (or as) the substrate carrier207/carrier engagement member 401 arrives at the substrate carrierhandler 215. In some embodiments, the type of the carrier 207 mayindicate the shape of the carrier, the dimensions of the carrier, thesize of the carrier, features of the carrier, the weight of the carrier,the maximum number of substrates that may be held in the carrier, thestatus of the carrier (e.g., fullness), the type of engagement and/orkinematic features, etc.

In an embodiment employing a closed loop feedback system, the controller237 of the substrate carrier handler 215 receives signals from one ormore sensors 233, 235 and/or encoders 240 a, 240 b and continually anddynamically adjusts the motion profile of the end effector 225 based onthe signal(s). A sensor 253 on the end effector 225 (or in synchronizedmotion with the end effector 225) may continuously (or frequently)detect the type, position and/or speed of the target substrate carrier207/carrier engagement member 401 through out the stroke of the endeffector 225 and send such information to the controller 237 so that thecontroller 237 may dynamically adjust the speed and/or position of theend effector 225 to match the target substrate carrier 207/carrierengagement member 401. Likewise, encoders 240 a, 240 b may be used toprovide the continuous (or frequent) position and/or speed of the targetsubstrate carrier 207/carrier engagement member 401 during the stroke ofthe end effector 225 and send such information to the controller 237 sothat the controller 237 may dynamically adjust the speed and/or positionof the end effector 225 to match the target substrate carrier207/carrier engagement member 401.

In a combination system of a closed loop feedback system and an openloop feedback system, a motion profile may initially be selected andtriggered based on a signal from a sensor 233 disposed before theposition of substrate carrier handler 215 on the path of the conveyor231 (or at the beginning of the end effector's stroke) and then theselected motion profile may be dynamically modified as the targetsubstrate carrier 207/carrier engagement member 401 moves through theend effector's stroke based upon feedback signals from the sensors 233,235 and/or encoders 240 a, 240 b. In some embodiments, additionalsensors (not shown) on the end effector 225 and/or on the substratecarrier 207 may detect other conditions upon which the controller 237may dynamically modify the motion profile. For example, an impact sensor(e.g., a transducer) on the substrate carrier 207 may be used to detectan amount of force being applied to the substrate carrier 207 by the endeffector 225 that exceeds a threshold amount of acceptable force. Thesensor may be coupled to a wireless transmitter adapted to send a signalto the controller 237 indicating that the position of the end effector225 should be adjusted to reduce the force being applied or that thetransfer should be aborted.

Assuming the end effector 225 is properly positioned relative to thetarget substrate carrier 207, following step 307 and/or step 309 in theprocess of FIG. 3 is step 311. At step 311, the controller 237 controlsthe substrate carrier handler 215 such that the end effector 225 israised (e.g., the horizontal guide 221 is raised on the vertical guides217, 219 to raise the end effector 225) while continuing tosubstantially match the horizontal speed (and/or instantaneous position)of the end effector 225 to the speed (and/or instantaneous position) ofthe target substrate carrier 207. The raising of the end effector 225causes the kinematic pins 229 thereof to come into engagement withconcave features 407 on the bottom of the target substrate carrier 207.Thus the end effector 225 is moved to an elevation at which the conveyor231 transports substrate carriers 207. In this manner, the end effector225 contacts the bottom of the target substrate carrier 207 (as shown inFIG. 4B). In one or more embodiments of the invention, the end effector225 preferably contacts the target substrate carrier 207 withsubstantially zero velocity and/or acceleration as described furtherbelow with reference to FIGS. 8A-D. As the end effector 225 continues tobe raised (while the end effector continues to substantially matchhorizontal speed and/or position with the target substrate carrier 207),the target substrate carrier 207 (and in particular its top flange 402)is lifted out of engagement with the carrier engagement member 401 ofthe conveyor 231, as illustrated in FIG. 4C.

Next, in step 313 of FIG. 3, the controller 237 controls the substratecarrier handler 215 to decelerate horizontal motion of the end effector225 slightly, thereby decelerating the target substrate carrier 207. Thedegree of deceleration is such that the target substrate carrier 207continues to move in the direction indicated by the arrow 403, but at aslower speed than the conveyor 231. This allows the carrier engagementmember 401 (which had engaged the flange 402 of the target substratecarrier 207) to move ahead of the flange 402, as indicated in FIG. 4D.Once the carrier engagement member 401 has moved out from underneath theflange 402 (as shown in FIG. 4D), the end effector 225 may beaccelerated again, so that the horizontal speed of the end effector 225and the target substrate carrier 207 supported thereon againsubstantially matches the horizontal speed of the conveyor 231 toprevent another substrate carrier being transported by the conveyor 231(e.g., substrate carrier 409 in FIG. 4D) from colliding with the targetsubstrate carrier 207.

In step 315 in FIG. 3, the end effector 225 is lowered (e.g., bylowering the horizontal guide 221 along the vertical guides 217, 219) tolower the target substrate carrier 207 away from the conveyor 231. Thelowering of the target substrate carrier 207 is illustrated in FIG. 4E.The end effector 225, having the target substrate carrier 207 supportedthereon, may then be decelerated (step 317, FIG. 3) and brought to ahalt. As stated, in at least one embodiment of the invention, theabove-described end effector 225 accelerations, decelerations, raisingsand/or lowerings may be defined by the motion profile determined for theend effector 225. (Exemplary motion profiles are described below withreference to FIGS. 8A-8D).

In step 319, the substrate carrier handler 215 may transport the targetsubstrate carrier 207 supported on the end effector 225 to one of thedocking stations 203 (FIG. 2A). Alternatively, if the loading station201 includes one or more storage shelves or other storage locations(e.g., storage shelf 239, shown in phantom in FIG. 2A, and adapted tostore a substrate carrier), the substrate carrier handler 215 maytransport the target substrate carrier 207 to one of the storagelocations. (Other and/or more storage locations may be employed). Theprocess of FIG. 3 then ends in step 321.

Assuming that the target substrate carrier 207 is brought to one of thedocking stations 203, the target substrate carrier 207 may be handed offby the substrate carrier handler 215 to the docking gripper 211 of therespective docking station 203. The target substrate carrier 207 thenmay be docked at the docking station 203, and opened by the substratecarrier opener 213 of the docking station 203 to allow extraction of atarget substrate from the target substrate carrier 207 (e.g., by asubstrate handler such as the FI robot 119 of FIG. 1). The extractedsubstrate may be transferred to a processing tool associated with thesubstrate loading station 201 (e.g., the processing tool 113 of FIG. 1)and one or more fabrication processes may be applied to the substrate bythe processing tool. Upon completion of the processing in the processingtool, the substrate may be returned to the target substrate carrier 207at the docking station 203 and the target substrate carrier 207 may beclosed and undocked from the docking station 203. The substrate carrierhandler 215 then may transport the target substrate carrier 207 awayfrom the docking station 203 and to a position just below the conveyor231 (e.g., assuming the substrate carrier 207 is to be returned to theconveyor 231 rather than stored at a storage location such as thestorage location 239). That is, with the substrate carrier 207 supportedon the end effector 225, the horizontal guide 221 may be moved near theupper ends 217 a, 219 a of the vertical guides 217, 219, and the support223 may be moved to the upstream end 221 a of the horizontal guide 221.The substrate carrier 207 then may be transferred back onto the conveyor231 as described below with reference to FIGS. 5-6E.

An exemplary process that may be performed in accordance with theinvention for loading a target substrate carrier 207 onto the conveyor231 will now be described with reference to FIGS. 5-6E. FIG. 5 is a flowchart that illustrates the inventive substrate carrier loading process.FIGS. 6A-6E are schematic side views showing various stages of theprocess of FIG. 5.

The process of FIG. 5 starts at step 501 and continues with step 503. Atstep 503 the controller 237 receives a signal (e.g., from the sensor 233or 235) indicating the presence of a vacant carrier engagement member401 of the conveyor 231. In response to this signal, in step 505, thecontroller 237 controls the substrate carrier handler 215 so that theend effector 225 (with the target substrate carrier 207 to betransferred to the conveyor 231 thereon) is accelerated along thehorizontal guide 221 to substantially match the motion of the vacantcarrier engagement member 401 (and/or the conveyor 231). For example,the end effector 225 may substantially match the speed and position ofthe vacant carrier engagement member 401 in the horizontal direction. Asstated previously, in one or more embodiments, the end effector 225 maynot be positioned at the same location as the trigger sensor (e.g.,sensor pair 233 b, 233 b′ of FIG. 2B). In such instances it may benecessary to delay acceleration of the end effector 225 in step 505 tocompensate for the differing positions of the end effector 225 and thetrigger (or launch) sensor.

In at least one embodiment of the invention, prior to accelerating theend effector 225 so that it substantially matches the position and speedof the vacant carrier engagement member 401 (step 505), the controller237 employs the sensor 233 or one or more encoders 240 a, 240 b coupledto the conveyor 231 to determine a speed of the conveyor 231. Positionof the conveyor 231 also may be determined. Based on the speed of theconveyor 231, the controller 237 may determine a motion profile for theend effector 225 and direct motion of the end effector 225 in accordancewith the motion profile to substantially match the speed and position ofthe end effector 225 (with the target substrate carrier 207 thereon) tothe vacant carrier engagement member 401 onto which the target substratecarrier 207 is to be loaded. The motion profile may be “predetermined”,such that the controller 237 only allows the end effector 225 to beginperforming a load operation (e.g., begin accelerating) if the speed ofthe conveyor 231 is within a predetermined speed range (e.g., a rangethat ensures that the end effector 225 will be properly aligned with thevacant carrier engagement member 401 if the end effector 225 isaccelerated in accordance with the predetermined motion profile);otherwise, the process of FIG. 5 ends.

Alternatively, the controller 237 may employ the speed of the conveyor231 to determine a motion profile for the end effector 225, for example,using a look up table of predetermined motion profiles, using analgorithm to calculate the motion profile, etc. It will be understoodthat carrier engagement member speed, rather than conveyor speed may bemeasured and employed to determine a motion profile or whether to employa predetermined motion profile for the end effector 225. Each motionprofile may include all of the accelerations, decelerations, raisingsand lowerings (described below) employed by the end effector 225 duringa load operation. (Exemplary motion profiles are described below withreference to FIGS. 8A-8D).

FIG. 6A shows the end effector 225 being moved at a substantiallymatching velocity with the conveyor 231, and with the flange 402 of thetarget substrate carrier 207 below and slightly behind the carrierengagement member 401 on which the target substrate carrier 207 is to beloaded. In this manner, the target substrate carrier 207 may be raisedwithout the flange 402 being obstructed by the carrier engagement member401 during transfer of the target substrate carrier 207 to the conveyor231 as described below. In general, the flange 402 of the targetsubstrate carrier 207 may be positioned at any location that allows thetarget substrate carrier 207 to be raised without contacting the carrierengagement member 401 on which the target substrate carrier 207 is to beloaded and the carrier engagement member (and/or a substrate carrierpositioned thereon) that follows the carrier engagement member 401 onwhich the target substrate carrier 207 is to be loaded.

Following step 505 is step 507 at which the relative horizontalpositioning of the target substrate carrier 207 and the carrierengagement member 401 are sensed (e.g., by the sensor 235, FIG. 2A). Forexample, if the sensor 235 comprises a light source/detector pair, thesensor 235 may emit a beam of light toward the vacant carrier engagementmember 401 (or the conveyor 231) that is only detected by the sensor 235if the end effector 225 is properly positioned relative to the vacantcarrier engagement member 401 (as described previously with reference toFIGS. 2C-2D). As described above, various closed and open loop feedbackarrangements may be used.

FIG. 2E is a perspective view of a portion of the end effector 225illustrating the sensor 235 positioned to detect a portion 249 of acarrier engagement member 401 that couples the carrier engagement member401 to the conveyor 231. Specifically, the portion 249 of the carrierengagement member 401 comprises a notch 251 that is angled to reflectlight beam 241 (emitted by the sensor 235) back toward the sensor 235when the end effector 225 is properly positioned below the carrierengagement member 401 for a load operation. Other configurations may beemployed. For example, the one or more encoders 240 a, 240 b or otherpositioning devices that directly measure conveyor speed may providesuch information to the controller 237 (e.g., continuously) such thatthe controller 237 may track conveyor position during a load (or unload)operation.

In at least one embodiment of the invention, if the end effector 225 isnot properly positioned relative to the vacant carrier engagement member401, then the process of FIG. 5 ends. Alternatively, in anotherembodiment of the invention, in step 509 any necessary adjustments maybe made in the relative horizontal positioning of the target substratecarrier 207 and the carrier engagement member 401 (e.g., to ensure thatthe flange 402 does not contact the carrier engagement member 401 whenthe target substrate carrier 207 is raised as described below). Forexample, the controller 237 may accelerate and/or decelerate the endeffector 225 until a proper alignment signal is received from the sensor235. During such position adjustment, the horizontal speed of the targetsubstrate carrier 207 and the horizontal speed of the conveyor 231and/or the carrier engagement member 401 may remain substantiallymatched. In yet another embodiment of the invention, steps 507 and 509may be eliminated (e.g., if a predetermined motion profile is employedthat is correlated to the speed of the conveyor 231 and/or launchtime/position of the end effector 225). In such an embodiment, thesensor 235 may be eliminated.

Assuming the end effector 225 is properly positioned relative to thevacant carrier engagement member 401, in step 511, and shown in FIG. 6B,the end effector 225 is raised, by raising the horizontal guide 221along the vertical guides 217, 219 (FIG. 2A), so that the targetsubstrate carrier 207 and particularly its flange 402, are brought up tothe level of the carrier engagement member 401. As shown in FIG. 6B, theflange 402 is positioned slightly above the carrier engagement member401 (e.g., for loading thereon as described below).

Next, as represented by step 513 and shown in FIG. 6C, the targetsubstrate carrier 207 is accelerated to bring the flange 402 of thetarget substrate carrier 207 above the carrier engagement member 401 ofthe conveyor 231. The target substrate carrier 207 is then decelerated,so that the horizontal speed of the target substrate carrier 207 againsubstantially matches the horizontal speed of the conveyor 231. Next, asillustrated in FIG. 6D and represented by step 515, the end effector 225is lowered (while continuing to substantially match the horizontal speedof the conveyor 231), to bring the flange 402 of the target substratecarrier 207 into engagement with the carrier engagement member 401 ofthe conveyor 231, thereby handing off the target substrate carrier 207to the carrier engagement member 401. In one or more embodiments of theinvention, the target substrate carrier 207 preferably contacts thecarrier engagement member 401 with substantially zero velocity and/oracceleration as described further below with reference to FIGS. 8A-8B.The substrate carrier handler 215, under control of the controller 237,continues to lower the end effector 225, (e.g., while continuing tosubstantially match the horizontal speed of the conveyor 231), so thatthe kinematic pins 229 of the end effector 225 are disengaged from thefeatures 407 on the bottom of the target substrate carrier 207. Anexemplary result of step 517 is illustrated in FIG. 6E.

After the end effector 225 is disengaged from the target substratecarrier 207, in step 519 the end effector 225 is decelerated (e.g.,halted) and the process of FIG. 5 ends (step 521). Meanwhile, the targetsubstrate carrier 207, which is supported via its flange 402 by thecarrier engagement member 401 of the conveyor 231, is transported awayfrom the loading station 201 by the conveyor 231. As stated, in at leastone embodiment of the invention, the above-described end effector 225accelerations, decelerations, raisings and/or lowerings may be definedby the motion profile determined for the end effector 225.

Thus the substrate loading station 201 provided in accordance with theinvention, and in particular the substrate carrier handler 215 operatingunder the control of the controller 237, functions to unload substratecarriers from a moving conveyor and to load substrate carriers onto themoving conveyor. In this manner, the inventive substrate loading stationand substrate carrier handler may reduce substrate dwell time within afabrication facility, work-in-progress, and working capital andmanufacturing costs.

In accordance with the invention, the controller 237 may be programmedto perform one or both of the processes of FIGS. 3 and 5. Also theprocesses of FIGS. 3 and 5 may be embodied in one or more computerprogram products. Each computer program product may be carried by amedium readable by a computer (e.g., a carrier wave signal, a floppydisk, a hard drive, a random access memory, etc.).

In at least one embodiment of the invention, the inventive substrateloading station 201 may be configured to automatically retract the endeffector 225 away from the conveyor 231 in the event of a power failure,emergency shutdown (described below), etc. For example, the controller237 may include an end effector retraction routine which automaticallyretracts the end effector 225 (and/or the horizontal guide 221) awayfrom the conveyor 231 in response to an unscheduled interrupt such as apower failure, emergency shutdown, or the like. Further, the endeffector 225 (and/or the horizontal guide 221) may be biased so that theend effector 225 (and/or the horizontal guide 221) automaticallyretracts when power is removed from the substrate loading station 201.Any suitable biasing mechanism such as springs, gravity, air cylinders,ball screws, lead screws, etc., may be employed. The above mentioned endeffector retraction routine may be implemented, for example, as one ormore computer program products.

Exemplary parameters that may affect design of the substrate loadingstation 201 include, for example, (1) conveyor speed; (2) horizontaland/or vertical speed at which the substrate carrier handler 215 canmove the end effector 225; (2) horizontal and/or vertical accelerationand deceleration that may be applied to the end effector 225 of thesubstrate carrier handler 215; (4) horizontal and vertical range ofmovement of the end effector 225 of the substrate carrier handler 215;(5) distance between adjacent substrate carriers 207 transported by theconveyor 231; (6) elevation at which the conveyor 231 transports thesubstrate carriers 207; (7) vertical distance a substrate carrier 207should be lifted to clear the carrier engagement member 401 of theconveyor 231 used to transport the substrate carrier 207; (8) height(e.g., vertical dimension) of each substrate carrier 207; (9) distance asubstrate carrier 207 must be lowered, after being released from acarrier engagement member 401, to allow substrate carriers beingtransported by the conveyor 231 to pass over the released substratecarrier 207 without striking the released substrate carrier 207; (10)the type of carrier engagement member employed; and/or (11) othersimilar parameters.

For example, in at least one embodiment of the invention, the inventivesubstrate carrier handler 215 should be capable of (1) achieving amaximum horizontal speed for the end effector 225 that is greater thanor equal to the horizontal speed of the conveyor 231; (2) raising theend effector 225 to an elevation sufficient to disengage and clear asubstrate carrier 207 from a conveyor carrier engagement member 401; (3)moving at two or more horizontal speeds, such as a first horizontalspeed for matching conveyor speed and a second horizontal speed fortransporting a substrate carrier 207 to and from a docking station 203;(4) moving at two or more vertical speeds, such as a first verticalspeed for disengaging a substrate carrier 207 from or handing off asubstrate carrier 207 to the conveyor 231, and a second vertical speedfor transporting a substrate carrier 207 to and from a docking station203; and/or (5) performing all accelerations and decelerations of asubstrate carrier 207 supported by the end effector 225 (and requiredfor substrate carrier engagement with or disengagement from the conveyor231) without damaging a substrate or substrates contained in thesubstrate carrier 207.

Likewise, the substrate carrier handler 215 should operate so as tolower its end effector 225 to a sufficiently low level to service thelowest docking station 203. (If a storage shelf or other storagelocation is present that is lower than the lowest docking station 203,then the substrate carrier handler 215 should be further operative tolower the end effector 225 to service the lowest storageshelf/location). The horizontal range of travel for the end effector 225provided on the horizontal guide 221, and the mechanism for moving theend effector 225 should be such that the end effector 225 is able toaccelerate to a horizontal speed substantially matching conveyor speed,disengage a substrate carrier 207 from and/or engage a substrate carrier207 with the conveyor 231 (while avoiding a collision with othersubstrate carriers being transported on the conveyor 231), anddecelerate to a halt, all within the available horizontal range oftravel provided by the horizontal guide 221.

It is contemplated to include some or all of the above describedfeatures/parameters in one or more embodiments of the inventivesubstrate loading station.

Various factors and parameters that may be considered in designing aparticular embodiment of the inventive substrate loading station 201and/or programming the controller 237 (FIG. 2A) will now be discussedwith reference to FIGS. 7A-7D. FIGS. 7A and 7B are simplified frontelevational views of the inventive substrate loading station 201,similar to FIG. 2A. FIGS. 7C-7D are simplified schematic side views of asubstrate carrier during engagement with and/or disengagement from theconveyor 231 similar to FIGS. 4A-4E and 6A-6E.

The horizontal range of the end effector 225 of the substrate carrierhandler 215 is illustrated in FIG. 7A. The end effector 225 and thesupport 223 are shown in solid outline at 701 in a position at theupstream limit of movement of the end effector 225 along the horizontalguide 221 of the substrate carrier handler 215. The end effector 225 andthe support 223 are also shown in phantom at 702 in a position at thedownstream limit of movement of the end effector 225 along thehorizontal guide 221. A distance D_(HR) illustrated in FIG. 7Arepresents the maximum horizontal range of travel of the end effector225.

Selection of the horizontal range of travel DHR, in addition to beinginfluenced by the design factors discussed above, may also be influencedby the positioning of the docking stations 203 or shelves 239 (e.g., thenumber and/or horizontal span of the docking stations or shelves), thedesired footprint for the substrate loading station 201, the size of thefactory interface or processing tool coupled to the substrate loadingstation 201, and/or the like.

The vertical range of travel of the end effector 225 is illustrated inFIG. 7B. The end effector 225, the support 223 and the horizontal guide221 are shown in solid outline at 703 at the upper limit of the range ofvertical movement of the end effector 225. At that position, the endeffector 225 is at an elevation E_(H), which is high enough to clear theflange 402 of a substrate carrier 207 from a carrier engagement member401 of the conveyor 231 (see FIGS. 4B-4D).

Continuing to refer to FIG. 7B, the end effector 225, the support 223and the horizontal guide 221 are shown in phantom at 704 at the lowerlimit of the range of vertical movement of the end effector 225. At thatposition, the end effector 225 is at an elevation E_(L), which is thelowest elevation required to service the lowest docking station (orstorage location) of the substrate loading station 201. A distanceD_(VR) illustrated in FIG. 7B represents the maximum vertical range oftravel of the end effector 225 (e.g., D_(VR)=E_(H)−E_(L)). Othervertical ranges of travel may be employed.

Parameters which affect an operation for engaging or disengaging asubstrate carrier 207 from the conveyor 231 are illustrated in FIGS.7C-7D. FIG. 7C shows a distance D_(S) which separates two adjacentsubstrate carriers 207 being transported by the conveyor 231. Theseparation distance D_(S) is related to, but less than, a distanceD_(CEM) between the carrier engagement members 401, and is also relatedto a horizontal dimension of the substrate carriers 207. Increasing thedistance D_(S) eases load and unload operations by providing a largerspace and/or time period for raising, lowering, accelerating and/ordecelerating a substrate carrier 207 during load and unload operations.However, increasing the distance D_(S) generally decreases the number ofsubstrate carriers that may be transported by the conveyor 231.

As shown in FIG. 7D, in at least one embodiment of the invention, todisengage a substrate carrier 207 from the conveyor 231, the endeffector 225 raises the kinematic features 229 to an elevation equal toat least the elevation E_(CB) of the bottom of the substrate carrier207. More specifically, the kinematic features 229 are raised to anelevation greater than or equal to the elevation E_(CB) plus the heightH_(CEM) of the seat of the carrier engagement member 401 supporting thesubstrate carrier 207 (e.g., to clear the flange 402 of the substratecarrier 207 from the carrier engagement member 401). Prior to loweringthe disengaged substrate carrier 207, the end effector 225 isdecelerated to allow the carrier engagement member 401 to move ahead ofthe substrate carrier 207 by a total distance greater than a lengthL_(F) of the flange 402. Numerous other parameters may affect design ofthe inventive substrate loading station 201 and substrate handler 215.

The foregoing description discloses only an exemplary embodiment of theinvention; modifications of the above disclosed apparatus and methodswhich fall within the scope of the invention will be readily apparent tothose of ordinary skill in the art. For example, instead of employingtwo vertical guides in the substrate carrier handler illustrated above,only one vertical guide may be employed. Also, the substrate carrierhandler may be arranged with a vertical guide that is coupled forhorizontal movement along a horizontal guide instead of the horizontalguide coupled for vertical movement along vertical guides.

When the substrate carrier handler includes a vertical guide mounted formovement along a horizontal guide, the raising of the end effector todisengage a substrate carrier from a conveyor, or the lowering of theend effector to hand off the substrate carrier to the conveyor, may beaccomplished by raising or lowering the end effector along the verticalguide (e.g., rather than by raising the horizontal guide relative to apair of vertical guides). An actuator (such as a belt drive or leadscrew not shown) may be provided on the support 223 of the substratecarrier handler 215 to raise the end effector 225 relative to thehorizontal guide 221 to disengage a substrate carrier from the conveyor231, or to lower the end effector 225 toward the horizontal guide 221 tohand off the substrate carrier to the conveyor 231 (in addition to orinstead of raising/lowering the horizontal guide 221 along a verticalguide or guides).

The present invention may be employed to unload substrate carriers from,and load substrate carriers onto, a conveyor which transports substratecarriers in a vertical orientation. In such a case, the end effector 225may include a reorientation mechanism for reorienting a substratecarrier between vertical and horizontal orientations, as disclosed inU.S. patent application Ser. No. 60/407,452, filed Aug. 31, 2002,entitled “End Effector Having Mechanism for Reorienting a Wafer CarrierBetween Vertical and Horizontal Orientations”.

The present invention is illustrated with respect to single substratecarriers, but the present invention may be employed with substratecarriers that hold more than one substrate.

The particular embodiment of a substrate loading station illustratedherein includes docking stations arranged in a plurality of verticalstacks. However, the above-illustrated substrate loading station mayinclude only one vertical stack of docking stations, only one dockingstation or more than two vertical stacks of docking stations. Thesubstrate loading station may include one or more storage shelves and/orone or more other substrate carrier storage facilities which are notstorage shelves.

In the exemplary substrate loading station illustrated herein, thedocking stations are shown to include docking grippers that suspend asubstrate carrier to move it between docked and undocked positions.Alternatively the docking stations may include docking sleds orplatforms which support a substrate carrier from below, via thesubstrate carrier's bottom or sides, etc., while moving the substratecarrier between docked and undocked positions.

Preferably, the invention is employed in a substrate loading stationthat comprises a frame to which the vertical and horizontal guides arecoupled. In this manner, the preferred substrate loading station ismodular and may be quickly installed and calibrated. In the event thesubstrate loading station includes one or more storage shelves (e.g.,storage shelf 239 in FIG. 2A), each storage shelf also may be mounted onthe frame. By mounting both the substrate carrier handler and thestorage shelf or shelves to the frame, the substrate carrier handler andstorage shelves have a predetermined position relative to each other.This further facilitates installation and calibration, and is anotheradvantage of employing a modular substrate loading station. Similarly,other mechanisms such as dedicated mechanisms for loading and/orunloading substrate carriers from an overhead factory transport systemmay be advantageously mounted to the frame as described herein and, forexample, in previously incorporated U.S. patent application Ser. No.10/650,310, filed Aug. 28, 2003 and titled “System For TransportingSubstrate Carriers”.

In one aspect, the frame may be mounted to predetermined mountinglocations (e.g., predrilled bolt holes, etc.) on the clean room wall, oron the front wall of a chamber (e.g., a factory interface chamber).Preferably, the wall also has predetermined mounting locations to whichthe docking grippers or docking platforms are mounted. Additionally, thewall may have predetermined mounting locations to which a substratecarrier opening mechanism may be mounted. When the frame, the dockingmechanisms, and the substrate carrier opening mechanism are each mountedto predetermined locations on the same surface, the relative positionsof each are predetermined, and installation and calibration of thesubstrate loading station is facilitated.

Although the conveyor described herein has been illustrated as beingpositioned above the substrate loading station 201, it is alternativelycontemplated that the conveyor may be at or below the height of thesubstrate loading station or at another location positioned adjacent thesubstrate loading station.

The substrate loading station illustrated herein may be utilized toprovide substrates to a processing tool, a metrology location, or anyother location to which a substrate may be transported.

From the foregoing description, it will be understood that the inventivesubstrate loading station may be installed in association with a factoryinterface (FI) having an FI robot that transfers a substrate from adocking station of the substrate loading station to a load lock chamberof a processing tool (such as in the system of FIG. 1). Alternatively,the factory interface may be eliminated, and the load lock chamber mayinclude a substrate handler that transfers a substrate directly from thedocking station of the substrate loading station. As anotheralternative, the processing tool may operate at atmospheric pressurerather than under vacuum, so that the load lock chamber may beeliminated.

FIGS. 8A-8D are exemplary motion profiles for the end effector 225. Inat least one embodiment of the invention, when such motion profiles areemployed, only the sensor 233 (e.g., a “launch” sensor) need be employed(e.g., the sensor 235 may be eliminated). With reference to FIG. 8A,curve C1 illustrates end effector velocity along the x-axis (horizontaldirection in which the conveyor 231 travels) during a load operation.Curve C2 illustrates end effector velocity along the z-axis (verticaldirection) during a load operation. Curve C3 illustrates end effectorz-axis position and curve C4 illustrates end effector x-axis positionduring a load operation. FIG. 8B is similar to FIG. 8A, but shows thez-axis position data enlarged. FIGS. 8C-D are similar to FIGS. 8A-B, butillustrate x-axis velocity (curve C1′), z-axis velocity (curve C2′),z-axis position (curve C3′) and x-axis position (curve C4′) for the endeffector 225 during an unload operation. Note that FIGS. 8A-B shows thez-axis position data (curve C3) at a lower z-position during a start ofa substrate carrier load operation (e.g., to compensate for the size ofa substrate carrier).

With reference to FIGS. 8A-B and curves C1-C4, the end effector 225 mayperform similar railsings, lowerings, and accelerations as describedwith reference to FIG. 5 during a load operation. For example, and withfurther reference to FIGS. 5 and 6A-E, after receiving a trigger signalfor a load operation (step 503), the end effector 225 accelerates tomatch the velocity of the conveyor 231 in the x-direction (curve C1)between times T1 and T2 (step 505 and FIG. 6A). Thereafter, betweentimes T3 and T4, the end effector 225 (curve C3) is raised to the levelof the conveyor 231 (step 511 and FIG. 6B); for example, such that theflange 402 of the substrate carrier 207 to be loaded onto the conveyor231 is above the carrier engagement member 401 that is to receive thesubstrate carrier 207.

Between times T5 and T6, the end effector 225 is accelerated (curve C1)above the speed of the conveyor 231 (and then is decelerated back to thespeed of the conveyor 231) so that the flange 402 of the substratecarrier 207 is positioned above the carrier engagement member 401 (step513 and FIG. 6C). At time T7, with the flange 402 of the substratecarrier 207 positioned above the carrier engagement member 401, the endeffector 225 lowers (curve C3) and stops as the flange 402 contacts thecarrier engagement member 401 (as shown at time T8). The end effector225 then lowers until time T9 and the substrate carrier 207 remains onthe carrier engagement member 401. The substrate carrier 207 thereby istransferred to the conveyor 231 with substantially zero velocity and/oracceleration (e.g., at time T8) (steps 515 and 517 and FIGS. 6D-E). Forexample, because the end effector 225 stops as the flange 402 engagesthe carrier engagement member 401, transfer of the substrate carrier 207occurs with substantially zero velocity and acceleration in thez-direction (curve C2). Likewise, because end effector velocity in thex-direction is constant and matched to that of the conveyor 231 duringcarrier exchange (curve C1), transfer of the substrate carrier 207occurs with substantially zero acceleration in the x-direction. Further,in at least one embodiment, no motion occurs in the y-direction duringsubstrate carrier transfer. Accordingly, substrate carrier transfer maybe performed with substantially zero acceleration in three directionsand substantially zero velocity in at least two directions. Followingtime T9, the end effector 225 decelerates (step 519 and curve C1).

With reference to FIGS. 8C-D and curves C1-C4, the end effector 225 mayperform similar railsings, lowerings, and accelerations as describedwith reference to FIG. 3 during an unload operation. For example, andwith further reference to FIGS. 3 and 4A-E, after receiving a triggersignal for an unload operation (step 303), the end effector 225accelerates to match the velocity of the conveyor 231 in the x-direction(curve C1′) between times T1 and T2 (step 305 and FIG. 4A). Thereafter,between times T3 and T4, the end effector 225 is raised (curve C3′) sothat the kinematic features 229 engage the concave features 407 of thesubstrate carrier 207 to be unloaded from the conveyor 231 (step 311 andFIG. 4B). At time T4, the end effector 225 stops raising as thekinematic features 229 engage the concave features 407 (curves C2′ andC3′). Between times T4 and T5, the end effector 225 is raised further soas to lift the flange 402 of the substrate carrier 207 off of thecarrier engagement member 401 (step 311 and FIG. 4C). The substratecarrier 207 thereby is unloaded from the carrier engagement member 401with substantially zero velocity and/or acceleration (e.g., in the x, yand/or z-directions due to the halting of z-axis motion at time T4 priorto lifting the substrate carrier 207 from the carrier engagement member401 and due to speed matching between the end effector 225 and theconveyor 231). Following time T5, the end effector 225 decelerates andreaccelerates (step 313 and curve C1′) and lowers (step 315 and curveC3′) to clear the carrier engagement member 401 as previously describedand as shown in FIGS. 8C-D.

Accordingly, unloading/loading of substrate carriers from/onto a movingconveyor may occur with substantially zero velocity and/or accelerationin one or more directions, more preferably in two directions, and mostpreferably in all directions. Substantially zero velocity andacceleration in a vertical direction are preferred; and zero velocitiesand/or accelerations, rather than substantially zero velocities and/oraccelerations, during unloading/loading are more preferred. As usedherein, “zero velocity” or “zero acceleration” mean as close to zero aspossible given system variations such as conveyor height, conveyorspeed, actuator repeatability, etc., system limitations such ascontroller resolution, actuator resolution, end effector positiontolerances, etc., and/or the like. “Substantially zero velocity” or“substantially zero acceleration” mean sufficiently close to zero sothat a substrate carrier may be unloaded from and/or loaded onto amoving conveyor and/or carrier engagement member without damaging asubstrate contained within the substrate carrier and/or generatingpotentially damaging particles. For example, a substrate carrier may becontacted with a relatively small velocity. In one embodiment, an endeffector may be rapidly raised vertically and then slowed down to arelatively small or substantially zero velocity prior to contacting asubstrate carrier. A similar small (or substantially zero) accelerationalso may be employed. Similar load operations may be performed. In oneembodiment, substrates or substrate carriers are contacted in a verticaldirection with less than about 0.5 G of force, and in another embodimentwith less than about 0.15 G of force. Other contact force values may beemployed.

While the present invention has been described primarily with referenceto unloading/loading substrate carriers that contain only a single waferfrom/onto a moving conveyor, it will be understood that substratecarriers that contain multiple substrates similarly may be unloaded fromor loaded onto a moving conveyor. Further, the present invention may beemployed within systems that transport both single substrate carriersand multiple substrate carriers (e.g., 25 substrate carrier frontopening unified pods). Likewise, the present invention may be employedto unload individual substrates from and/or load individual substratesonto a moving conveyor (e.g., substrates that are not contained within aclosed substrate carrier). For example, substrates may be transportedvia a conveyor using an open substrate carrier, a substrate support, asubstrate tray or another substrate transport device that allows the endeffector 225 (or a modified version thereof) to directly place asubstrate on or remove a substrate from the substrate transport deviceof the conveyor using similar end effector movements and/or motionprofiles. Such individual substrates thereby may be transferred to adocking station or other load port, or directly into a load lock chamberand/or processing tool if desired. For example, a substrate may betransferred directly from the end effector 225 to a substrate handlingrobot of a factory interface and/or processing tool (e.g., via a direct“blade-to-blade” transfer or via an intermediate transfer location).Multiple individual substrates similarly may be unloaded/loadedfrom/onto a moving conveyor.

As relates to the foregoing description, the wafer carrier loadingstation of the present invention is adapted to interact with wafercarriers as they are being transported at high speeds along a conveyorof a wafer carrier transport system. During the process of removing aselected wafer carrier from the conveyor, for example, the end effectorof the wafer carrier handler is set in motion (or “launched”) to match avelocity or speed of a selected wafer carrier being transported by thetransport system, and to match a position relative to the movingconveyor occupied by the selected wafer carrier.

Both of these functions (i.e., speed-matching and position-matching) canbe performed by the loading station when the end effector is safelyvertically separated from the transport system and from the wafercarriers the transport system transports at high speeds. However it isthe preferably simultaneous combination of these functions with a thirdfunction of the loading station, i.e. changing the elevation of the endeffector relative to the transport system so as to match an elevation ofthe selected wafer carrier (elevation-matching), that begins a temporaryperiod of intersection between the loading station and the transportsystem. It is this temporary intersection from which an elevated riskfor unintended collisions (exclusive of the intended contact between theend effector and the selected wafer carrier) arises.

When the loading station and the transport system temporarily intersect,components of the loading station, components of the transportationsystem, the selected wafer carrier, and most likely a plurality ofnearby wafer carriers, are all preferably traveling at relatively highspeeds, increasing the potential for damage that could stem fromcollisions among those components and wafer carriers.

During the wafer carrier removal process, the temporary intersectionbetween the loading station and the transport system can start, evenbefore the end effector contacts the selected wafer carrier, whenportions (e.g., kinematic pins) of the end effector begin to occupy thesame elevation as portions of the wafer carriers being transported bythe transport system. The temporary intersection can continue during theperiod of time immediately after the end effector contacts and lifts theselected wafer carrier from the wafer carrier support member of theconveyor by which the transport system was supporting the selected wafercarrier. For example, during that time period, part or all of the endeffector may continue to occupy the same elevation as adjacent wafercarriers and other nearby wafer carriers being transported by thetransport system (e.g., wafer carriers not selected to be removed duringthe wafer carrier removal process). Only after the end effector is movedvertically to a sufficient extent so as to extract the end effector andthe selected wafer carrier from within the elevation of the movingconveyor and/or the other wafer carriers transported by the transportsystem, does the period of temporary intersection between the transportsystem and the loading station concluded, and the corresponding risk ofincreased unintended collisions is eliminated. Although the process bywhich the loading station places a selected wafer carrier on thetransport system differs from the wafer carrier removal process, thewafer carrier placement process also requires a similar temporary periodof intersection between the transport system and the loading station.For example, the temporary period of intersection of the placementprocess may start with the selected wafer carrier “breaking the plane”of the flow (or entering the elevation) of wafer carriers already placedon the rotating conveyor, and continue until the entire end effector(now empty), passes back through that plane.

Careful control of relative motion between the end effector of theloading station and the rotating conveyor of the transport system duringthe temporary period of intersection between the loading station and thetransport system is needed for the wafer carrier removal and placementprocesses to be performed smoothly. A loss of control over relativemotion between the end effector and the moving conveyor during thisperiod can result in at least three distinct modes of malfunction thatcan lead to unintended collision, for example: 1) the end effectorcontinuing to move at the intended speed and the conveyor, its motiveforce for rotation having been abruptly reduced or eliminated, slowingand/or coming to rest; 2) the conveyor continuing to rotate at theintended speed and the end effector, its motive force for linear motion(e.g. as provided by the horizontal guide of the wafer carrier handler)having been abruptly reduced or eliminated, slowing and/or coming torest; and 3) the conveyor and the end effector, both losing part or alltheir respective motive forces, and slowing at different rates. Otherpossible modes of malfunction that may contribute to the occurrence ofunintended collisions, such as loss of motive force for vertical motionof the end effector (e.g. as provided by the vertical guide of the wafercarrier handler), may also occur.

During normal operation, the different components of the overall system,e.g. sensors, high-precision actuators and a process controller orcontrollers, are adapted to cooperate so as to provide careful controlof relative motion between the end effector of the loading station andthe rotating conveyor of the transport system. However, unplanned eventsduring the temporary period of intersection between the transport systemand the loading station may impair this cooperation and interrupt ordestroy such careful control, potentially leading to substrate orequipment damage.

An example of such an unplanned event is a power failure within themanufacturing facility that threatens to cause or causes an interruptionin the transport system function or in the wafer carrier handler of theloading station function during a wafer carrier placement or removal.Functions of particular concern include the conveyor-rotation functionof the transport system, the speed-matching function of the horizontalguide of the wafer carrier handler, and the elevation-matching functionof the vertical guides of the wafer carrier handler.

Another such event is an emergency shutdown of the transport system orof the loading station itself, or of the entire manufacturing facility.Emergency shutdowns may be triggered, either automatically or manually,in response to many different causes (e.g., malfunction of a key systemor mechanism) and for many different reasons (e.g., prevention of injuryto personnel near the malfunctioning system, or prevention of damage toWIP wafers or adjacent systems and mechanisms).

Accordingly, the present invention comprises methods and apparatus forcausing an intersection condition, such as those described above, to beremoved upon the occurrence of a unscheduled event, most preferably uponthe occurrence of events tending to occur at unexpected times, such as apower failure or an emergency shutdown. In addition, examples of methodsand apparatus for ensuring an orderly cessation of the above-mentionedspeed-matching, position matching, and elevation matching between thetransport system and the loading station are provided.

Exemplary embodiments of methods and apparatus for retracting the endeffector of the loading station from the transport system, are describedbelow with reference to FIGS. 9A-9B, 10 and 11.

FIGS. 9A-9B are side elevational views of a wafer carrier loadingstation 801 in accordance with the present invention, shown adjacent arotatable conveyor 803 of a wafer carrier transport system 805. Asshown, the wafer carrier loading station 801 is performing a portion ofan unload procedure in accordance with the present invention, on aselected wafer carrier 807 carried along the conveyor 803 by a wafercarrier support member 808. The wafer carrier loading station 801inventively comprises a biasing device 809. The biasing device 809 isadapted to store sufficient energy to generate enough motive force tourge an end effector 811 of the wafer carrier loading station 801 awayfrom the conveyor 803 in the event of a loss of power (e.g. a powerfailure or an emergency shutdown) during an unload or a load operation.With reference to FIGS. 9A-9B, the wafer carrier loading station 801further comprises a frame 813 and a wafer carrier handler 815 supportedby and coupled to the frame 813. The wafer carrier handler 815 comprisesthe end effector 811, a horizontal guide 817 to which the end effector811 is movably coupled (e.g., via a support 819) and along which the endeffector 811 is adapted to be guided along a substantially horizontallinear path (not shown), and at least one vertical guide 821 to whichthe horizontal guide 817 is movably coupled and along which thehorizontal guide 817 is adapted to be guided along a substantiallyvertical linear path (not shown).

The exemplary embodiment of the biasing device 809 of the wafer carrierloading station 801 shown in FIGS. 9A-9B comprises a pushing mechanism825. The pushing mechanism 825 preferably comprises an enclosure 827, aresilient member 829, and a plunger 831. The resilient member 829 ispreferably compressibly enclosed within the enclosure 827, and theplunger 831 is operatively coupled to the resilient member 829 forreciprocal motion relative to the enclosure 827. The plunger 831comprises a distal end 833 adapted to be coupled to the horizontal guide817 of the wafer carrier handler 815 as shown in FIGS. 9A-9B. In thepreferred embodiment of FIGS. 9A-9B, the biasing device 809 is fixedlycoupled to the vertical guide 821 of the wafer carrier handler 815 for acompact shape and good alignment. Other less-preferred embodiments (notshown) include different coupling modes for the biasing device 809, suchas a particular embodiment in which the biasing device 809 is fixedlycoupled to the frame 813 of the wafer carrier loading station 801.

In operation, the biasing device 809 of the wafer carrier loadingstation 801 draws upon retained energy to generate and apply a motiveforce to the horizontal guide 817 of the wafer carrier handler 815. Themotive force generated by the biasing device 809 preferably operates atleast when power to the vertical guide 821 of the wafer carrier handler815 is significantly reduced or is cut off entirely. At such a time, thebiasing device 809 applies a motive force to the horizontal guide 817and urges the horizontal guide 817 downward so as to move the endeffector 811 away from a first elevation 835 (FIG. 9A) corresponding toa condition of intersection between the wafer carrier loading station801 and the wafer carrier transport system 805 (as described above).Preferably the biasing device 809 urges the end effector 811 from thefirst elevation 835 to a second elevation 837 (FIG. 9B) at which theabove-mentioned intersection condition no longer exists, as demonstratedby the existence of a positive vertical clearance 839 between the wafercarrier 807 and a wafer carrier 841 that continues to be transported bythe wafer carrier transport system 805.

In a preferred embodiment, the motive force generated by the biasingdevice 809 is large enough so that when it is combined with the force ofgravity, the total force is sufficient, in the absence of upward forcegenerated by the vertical guide 821, to urge the horizontal guide 817 ofthe wafer carrier handler 815 downward along the vertical guide 821.Also in a preferred embodiment, the motive force generated by thebiasing device 809 is not so large as to prevent the vertical guide 821of the wafer carrier handler 815 from raising the horizontal guide 817,e.g., from the second elevation 837 to the first elevation 835,repeatably and reliably over the expected lifetime of the vertical guide821, as well as with a high degree of precision and/or controllability.In the context of the exemplary embodiment of the biasing device 809represented by the pushing mechanism 825 of FIGS. 9A-10A, those withskill in the art will recognize that the resilient member 829 of thepushing mechanism 825 may take many different forms in accordance withthe present invention, such as, e.g., a coiled spring, or an aircylinder.

FIG. 10 is a rear elevational view illustrating the wafer carrierhandler 815 of the wafer carrier loading station 801 illustrated inFIGS. 9A-9B. As shown in FIG. 10, a biasing device 809 is coupled toeach of two vertical guides 821 of the wafer carrier handler 815. Suchan arrangement divides the generation of motive force roughly equallybetween the two widely-spaced biasing devices 809, enabling awell-balanced application of the motive force to the horizontal guide817 of the wafer carrier handler 815.

FIG. 11 is a rear elevational view illustrating the wafer carrierhandler 815 of FIGS. 9A-9B and 10 operatively coupled to a controller843, the controller 843 being further coupled to an uninterruptiblepower supply 845 and adapted to operate the wafer carrier handler 815via power supplied from the uninterruptible power supply 845 so as tocause the end effector 811 of the wafer carrier handler 815 to retractfrom the conveyor 803 (FIGS. 9A-9B) of the wafer carrier loading station801 (FIGS. 9A-9B), e.g. in the event of a power failure or an emergencyshutdown (e.g., the uninterruptible power supply may supply power toboth the controller 843 and the wafer carrier handler 815). As shown inFIG. 11, the biasing devices 809 of FIGS. 9A-9B and 10 are absent fromthe vertical guides 821 of the wafer carrier handler 815. Theuninterruptible power supply 845 is adapted to command the controller843 to cause the wafer carrier handler 815 to retract the end effector811 from an intersection with the wafer carrier transport system 805(FIGS. 9A-9B), and to provide emergency power to the controller 843 andthe wafer carrier handler 815 in the absence of normal power.

In operation, a unscheduled event occurs, such as a power failure or anemergency shutdown, while the wafer carrier handler 815 and the wafercarrier transport system 805 (FIG. 9A-9B) temporarily intersect during awafer carrier removal process. The uninterruptible power supply 845,which may be adapted to be activated upon the occurrence of aunscheduled event such as a power failure or an emergency shutdown,activates. The uninterruptible power supply 845 provides emergency powerto the controller 843 to prevent a discontinuity in the function of thecontroller 843, and commands the controller 843 to operate the wafercarrier handler 815 so as to cause the wafer carrier handler 815 toeliminate the temporary intersection between the wafer carrier handler815 and the wafer carrier transport system 805 (FIG. 9A-9B) existing atthe time of the unscheduled event. The controller 843 operates the wafercarrier handler 815 accordingly, and the temporary intersection iseliminated, preferably as soon after the occurrence of the unscheduledevent as possible.

In a preferred embodiment, the controller 843 is adapted to control thewafer carrier handler 815 in accordance with a predetermined retractionroutine. In one such embodiment, the predetermined retraction routinecomprises computer code resident on the controller 843. In another suchembodiment, the predetermined retraction routine comprises computer codestored other than on the controller 843 but accessible by the controller843 after the occurrence of the unscheduled event.

In an embodiment, the controller 843 is adapted to distribute emergencypower from the uninterruptible power supply 845 to the wafer carrierhandler 815 so as to permit the wafer carrier handler 815 to continuefunctioning to eliminate the intersection. In another embodiment (notshown), the uninterruptible power supply 845 is adapted to provideemergency power directly to the wafer carrier handler 815, precludingthe need for the controller 843 to distribute power indirectly. In apreferred embodiment, the controller 843 causes the horizontal guide 817as well as the vertical guides 821 to participate in the elimination ofthe intersection, with the horizontal guide 817 functioning to providehorizontal clearance with the wafer carrier transport system 805 (FIG.9A-9B) (especially with the wafer carrier support member 808 (FIG.9A-9B) of the wafer carrier transport system 805) and the verticalguides 821 functioning to provide vertical clearance as necessary. In aless-preferred embodiment, the controller 843 may cause only thevertical guides 821 to participate in the elimination of theintersection to provide vertical clearance.

In a further alternative embodiment the controller may be adapted tocause the substrate carrier handler's end effector to retract from theconveyor's transport path whenever the controller receives power fromthe uninterruptible power supply.

FIG. 12 is a simplified front, elevational view of an alternativeretraction mechanism for moving the end effector 811 of the waferloading station 801 away from the conveyor 803. With reference to FIG.12, an extension 1201 is attached to or formed within at least one ofthe vertical guides 821. A cam surface 1203 is formed on the extension1201 as shown. Other cam surface shapes may be used.

A switch 1205 is mounted to the horizontal guide 817, and a roller 1207is coupled to the switch 1205 and adapted to roll along the cam surface1203 of the extension 1201. The extension 1201 is positioned so that theroller 1207 only contacts the extension 1201 when the end effector 811enters an area where unwanted intersection between the end effector 811(and/or a carrier 807 supported by the end effector 811) and theconveyor 803 (or a carrier 807 supported by the conveyor 803) may occur.

As further shown in FIG. 12, a pneumatic cylinder 1209 is employed tobias the end effector 811 above the horizontal guide 817. For example,during normal operation of the wafer loading station 801, the pneumaticcylinder 1209 may be fully extended (as shown).

As the horizontal guide 817 is raised along the vertical guides 821, theroller 1207 contacts the cam surface 1203 of the extension 1201 andmoves toward the switch 1205, activating the switch 1205. Activation ofthe switch 1205 allows a circuit (not shown) to form that will cause theend effector 811 to retract toward the horizontal guide 817 in responseto a power failure or other unscheduled event (described previously).For example, the pneumatic cylinder 1209 may be caused to retract inresponse to a power failure or other unscheduled event. Note thatbecause of the extension 1201 and the switch 1205, retraction of the endeffector 811 only occurs when the end effector 811 is in a locationwhere unwanted intersection between the end effector 811 (and/or acarrier 807 supported by the end effector 811) and the conveyor 803 (ora carrier 807 supported by the conveyor 803) may occur. That is, the endeffector 811 will not retract (in the event of a power failure or otherunscheduled event) if the horizontal guide 817 is below the extension1201. Accordingly, inadvertent collisions between the end effector 811(and/or the carrier 807) and storage locations and/or docking stations(represented generally by reference numeral 1211) due to retraction ofthe end effector 811 may be avoided.

While the present invention has been described primarily with referenceto wafers, it will be understood that the invention also may be employedwith other “substrates” such as a silicon substrate, a mask, a reticle,a glass plate, etc., whether patterned or unpatterned; and/or withapparatus for transporting and/or processing such substrates.

Further, while the present invention has been disclosed in connectionwith exemplary embodiments thereof, it should be understood that otherembodiments may fall within the spirit and scope of the invention asdefined by the following claims.

1. A system for loading and unloading substrate carriers onto and off ofa transport system comprising: a substrate carrier handler adapted totransfer a substrate carrier between a docking station and a transportsystem, the substrate carrier handler including an end effector adaptedto support the substrate carrier; a controller coupled to the substratecarrier handler and operative to control the substrate carrier handlersuch that the end effector of the substrate carrier handler is operativeto selectively engage and disengage the substrate carrier to and fromthe transport system while the substrate carrier is in motion; and asensor coupled to the controller and operative to provide a signal tothe controller indicative of at least one of the type, position andspeed of the substrate carrier throughout a horizontal range of motionof the end effector, wherein the controller includes two or more storedmotion profiles and is operative to: dynamically adjust at least one ofthe speed and position of the substrate carrier handler based on thesignal from the sensor to match the substrate carrier if the adjustmentmay be performed within a load or unload horizontal range of motion ofthe end effector of the substrate carrier handler, and modify a selectedmotion profile as the substrate carrier moves through the horizontalrange of motion of the end effector based on the signal from the sensor.2. The system of claim 1 wherein the sensor includes at least one ofmotion detector, a speed detector, a pressure sensor, an impact sensor,a carrier type sensor, a motor encoder, and a carrier presence detector.3. The system of claim 1 wherein the information about the substratecarrier indicates at least one of a speed of a carrier, a position of acarrier, a type of encoder, an orientation of a carrier, a presence of acarrier, substrate carrier handler motor encoder information, transportsystem motor encoder information, and a speed of the transport system.4. The system of claim 1 wherein the sensor includes a plurality ofsensors adapted to provide a plurality of signals to the controllerindicative of a plurality of information about the substrate carrier andthe transport system.
 5. The system claim 4 wherein the motion profileis selected based on the information about the substrate carrier.
 6. Thesystem of claim 5 wherein the motion profile defines a motion of the endeffector during a load or unload operation.
 7. The system of claim 5wherein the controller is further operative to modify the selectedmotion profile based on the plurality of signals from the plurality ofsensors.
 8. The system of claim 4 wherein the plurality of sensorsgenerate the plurality of signals while a substrate carrier approachesthe substrate carrier handler on the transport system.
 9. The system ofclaim 4 wherein the plurality of sensors generate the plurality ofsignals while a substrate carrier is being removed from the transportsystem by the substrate carrier handler.
 10. The system of claim 4wherein the plurality of sensors generate the plurality of signals whilea substrate carrier support on the transport system approaches thesubstrate carrier handler.
 11. The system of claim 4 wherein theplurality of sensors generate the plurality of signals while a substratecarrier support on the transport system is being loaded with a substratecarrier by the substrate carrier handler.
 12. The system of claim 4wherein the plurality of sensors include at least one sensor disposed onthe end effector.
 13. The system of claim 4 wherein the plurality ofsensors include at least one sensor disposed on the substrate carrier.14. The system of claim 4 wherein the plurality of sensors include atleast one sensor disposed on the transport system.
 15. The system ofclaim 4 wherein the plurality of sensors include at least one sensordisposed adjacent the transport system.
 16. The system of claim 4wherein the plurality of sensors include at least one sensor disposed onthe substrate carrier handler.
 17. A method of loading and unloadingsubstrate carriers onto and off of a transport system comprising:sensing at least one of the position and speed of an approachingsubstrate carrier throughout a horizontal range of motion of an endeffector adapted to support the substrate carrier, wherein the substratecarrier is being transported on a transport system; determining asubstrate carrier type for the approaching substrate carrier; selectingan unload motion profile from among at least two stored motion profilesbased on at least one of the position and speed of the substrate carrierand based on the substrate carrier type; dynamically adjusting at leastone of the speed and position of a substrate carrier handler in theunload motion profile based on additional information sensed during anunload horizontal range of motion of an end effector of a substratecarrier to match the substrate carrier as the substrate carrier movesthrough the horizontal range of motion of the end effector; andunloading the substrate carrier from the transport system using theadjusted unload motion profile.
 18. A method of loading and unloadingsubstrate carriers onto and off of a transport system comprising:determining an available substrate carrier support on a transportsystem; sensing first information about the substrate carrier support;sensing at least one of position and speed of a substrate carrier to beloaded onto the substrate carrier support throughout a horizontal rangeof motion of an end effector of a substrate carrier handler; determininga substrate carrier type for the substrate carrier; selecting a loadmotion profile from among at least two stored motion profiles based onthe first and second information and based on the substrate carriertype; dynamically adjusting at least one of the speed and position ofthe load motion profile based on additional information sensed during aload horizontal range of motion of the end effector of the substratecarrier handler to match the substrate carrier as the substrate carriermoves through the horizontal range of motion of the end effector; andloading the substrate carrier from the transport system using theadjusted load motion profile.